The present invention relates generally to an apparatus for vapor production and more particularly to a compact smoke generator capable of emitting either a dense and extremely thin, laminar filament of smoke or large streams of smoke.
The use of smoke generation to aid flow visualization has long been known in the field of wind tunnel research. Early smoke generators had several major drawbacks, however; they were bulky and could only produce large volumes of turbulent smoke. Recently, compact smoke generators, such as Parrish, U.S. Pat. No. 3,964,304 have been developed. A compact generator does not significantly disturb airflow around the test article, a problem associated with former models. As aerodynamics technology has increased, however, the need has arisen for a compact smoke generator which can emit an extremely thin and stable filament of smoke. Such a filament is very useful for visualizing flow in detail.
A stable filament of smoke with small diameter and high density has not been provided by prior art generators because the circumference of the smoke exit hole in such generators was subject to atmospheric cooling which causes condensation of smoke generating fluid at the smoke exit. A smoke exit hole located at the termination of the smoke feed tube cannot avoid atmospheric cooling. Other prior art devices generated smoke in a chamber and fed the smoke to a small tube. Such devices provide low density smoke streams, however. Thus, it is seen that prior art smoke generators produced either large diameter or low density smoke streams.
It is therefore an object of the present invention to provide a smoke generator capable of emitting an extremely thin laminar stream of dense smoke.
Another object of the present invention is a smoke generator with the capability of indicating airflow around a model in an operating wind tunnel, with a negligible adverse effect thereon.
A further object of the present invention is to provide a smoke generator capable of generating a large volume of smoke.
Another object of the present invention is to provide a generating oil feed tube which is directly heated by electrical resistance.
Yet another object of the present invention is to provide a smoke generator which makes efficient use of smoke generating oil, is easy to operate, and which requires minimal adjustment while in operation.
It is another object of the present invention to provide a smoke exit hole with a circumference that is directly heated by locating the hole away from the termination of, and in the wall of, the oil feed tube.